MP2602 – 28V, 1A LINEAR LI-ION BATTERY CHARGER WITH TRICKLE CHARGE

MP2602 Rev.1.3

www.MonolithicPower.com

8

1/25/2010

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Charge Status Indicator (CHG)

The MP2602 has an integrated charge status

pin that remains low while the battery is

charging. Once the charge current has reduced

the CHG pin will become high impedance.

Under full charge conditions, certain systems

may draw a very narrow current pulse that

exceeds the IBF threshold. The

CHG indicator

may glitch. It is desirable to blank the

CHG glitch so that the system can properly

indicate full charge conditions to the end user.

A simple solution is to add a RC filter on the

CHG pin to filter out the possible CHG glitch,

as shown in Figure 5.

Negative Thermal Coefficient (NTC)

Thermistor

The MP2602 has a built-in NTC resistance

window comparator. If configured as the typical

application circuit as indicated in Figure 1, the

temperature range of 0°C to 50°C for the

TH11-4H104F NTC resistor.

Thermal Protection

The MP2602 has proprietary thermal protection

to prevent the IC from overheating. When in

thermal protection mode, the charge current

becomes a saw-tooth waveform instead of a

DC current. The average current of the saw-

tooth waveform will be lower than the

programmed DC charge current to prevent the

IC from overheating. The frequency and

amplitude of the saw-tooth current waveform

can be altered by changing the capacitance

value connected to the SS pin. Operating in

thermal protection mode will slow down the

charging process. Lowering the input voltage

and enhancing thermal dissipation to the

environment can effectively prevent the IC from

going into thermal protection mode.

MP2602

BATT

ISET

IBF

SS

GND

10

9

8

7

6

IN

CHG

ACOK

EN

NTC

1

2

3

4

5

JP4

JP1

JP2

JP3

VIN

BAT

GND

GND

CHG

ACOK

EN

NTC

Figure 5—Filtered Charge Status with GPIO Connection